1. Field of the Invention
The present invention relates to compositions for promoting growth of collagen in human skin, and more particularly, to topical preparations containing live yeast cell derivative (LYCD).
2. Discussion
At least since the time of Cleopatra, people have applied substances to their skin in an attempt to appear younger. While many of these substances did little to improve the appearance of skin, most of the clinically proven treatments for rejuvenating skin--.alpha.- and .beta.-hydroxy acids, retinoic acid, chemical peels, dermabrasions, laser resurfacings--have involved substantial irritation of the skin. For example, people who use hydroxy acids or retinoic acid often complain of erythema (redness), burning, stinging, and peeling.
Moreover, it appears that skin irritation is not simply a side effect of these treatments, but is necessary for their efficacy. For example, physicians' attempts to create products and procedures that reduce the side effects of chemical treatments were accompanied by a diminution of efficacy. Similarly, though many physicians have switched from harsh CO.sub.2 laser resurfacing to "gentle" erbium lasers, they report that skin rejuvenation occurs only with comparable skin destruction
Current "irritant-based" treatments suffer other drawbacks. For example, the effectiveness of these treatments appears to diminish with long-term exposure or increased use. Research suggests that prolonged exposure to retinoic acid, .alpha.- and .beta.-hydroxy acids, and phenolic peels does not result in a continual improvement in skin appearance. A similar drawback occurs with CO.sub.2 laser resurfacing, where physicians have noted that skin rejuvenation results only from moderate skin destruction. If aggressive laser destruction is performed in an attempt to correct severe skin damage, scarring can develop.
In recent years, physicians have begun exploring ways to improve skin appearance without irritation, but their efforts have met with limited success. For example, U.S. Pat. No. 4,942,031 discloses topical preparations containing live yeast cell derivative (LYCD) for reducing skin wrinkles. However, the disclosed anti-wrinkling compositions also contain retinoic acid, which, as discussed above, can irritate the skin. Another therapy, which is described in U.S. Pat. No. 5,709,868, discloses treating skin with lipoic acid but not in combination with LYCD. Moreover, the formulations disclosed in the latter patent focus on free radical scavenging and therefore do not target the result of the present invention--stimulation of collagen growth to rejuvenate skin. Thus, although the '868 patent may arguably improve skin appearance, it does so in a substantially different way than the present invention.
The present invention is directed to overcoming, or at least minimizing, one or more problems described above by using a synergistic combination of components, including LYCD.